Book Review: Gender Responsive Investment Handbook Addressing the Barriers to Financial Access for Women\u27s Enterprise

Review of Gender Responsive Investment Handbook Addressing the Barriers to Financial Access for Women’s Enterprise by Vanessa Erogbogbo, Esther Eghobamien and Elizabeth Pimentel. Commonwealth Secretariat, 2013

Factors governing seed recalcitrance in two species of contrasting storage longevity.

Doctor of Philosophy in Life Sciences. University of KwaZulu-Natal, Durban, 2017.Abstract available in PDF file

Biotyping Saccharomyces cerevisiae strains using matrix assisted laser desorption/ionization time of flight mass spectrometry (MALDI-TOF MS)

Thesis (M.Sc.)-University of KwaZulu-Natal, Westville, 2011.In clinical diagnosis and fermentation industries there is a need for a method that allows for the differentiation of yeast to the strain level (biotyping). The ideal biotyping method should be accurate, simple, rapid and cost-effective, and capable of testing a large number of yeast isolates. Matrix assisted laser desorption/ionization time of flight mass spectrometry has emerged as a powerful biotyping tool for the identification of bacteria and clinical yeast isolates, mainly Candida. It has been found that the MALDI-TOF MS signals from yeast are harder to obtain than from bacteria. It has been reported by several research studies that a cell lysis step is required to obtain a mass spectral signal for clinical Candida strains. To date an optimized sample preparation protocol has not been devised for the biotyping of S. cerevisiae strains. Studies on the identification of yeast using MALDI-TOF MS have focused primarily on clinical Candida yeast isolates but have included very few S. cerevisiae strains. Furthermore these yeast identification studies using MALDI-TOF MS have only achieved identification to the species and not strain level. A major limiting attribute of MALDI-TOF MS for the accurate identification of microbes, is its dependency on a comprehensive mass spectral database. Bruker Daltonics is a pioneer and leader in providing innovative life science tools based on mass spectrometry thus the Bruker Daltonics mass spectral database and state-of-the-art instruments and accompanying software were selected for this study. The Bruker Daltonics mass spectral database currently holds three thousand seven hundred and forty microorganisms of which only a mere seven are S. cerevisiae strains. Initially in this study, a number of parameters of a generic ethanol/formic acid protein extraction procedure as originally described by Bruker Daltoincs were considered in the development of a sample preparation protocol that yielded characteristic and highly reproducible MALDI-TOF mass spectra. The parameters considered included cell number, alcohol fixation, matrix solution and media. It was found that using the optimized sample preparation protocol unique and highly reproducible mass spectral profiles were obtained for all three S. cerevisiae strains. Multivariate analysis confirmed that the differences between all three S. cerevisiae strains were statistically significant. For quality assurance, the spectra of the three strains were sent for evaluation by Bruker Daltonics and were deemed suitable for the purpose of biotyping. The newly created ethanol/formic acid extraction procedure was used to generate an S. cerevisiae mass spectral database comprising of forty-five S. cerevisiae strains within a local context but also of global significance. The accuracy of the mass spectral database was assessed using blind coded S. cerevisiae strains obtained from the Agricultural Research Council Infruitec-Nietvoorbij (Institute for Deciduous Fruit, Vines and Wine), Stellenbosch, South Africa. It was found that S. cerevisiae identification to the species and more importantly strain level was achievable with relatively good accuracy. To determine the potential application of MALDI-TOF MS as an accurate method for S. cerevisiae strain identification in industry, blind coded S. cerevisiae strains were obtained from Natal Cane Products and subjected to MALDITOF MS analysis. It was found that four of the pure cultures submitted were correctly identified to the strain level and the three S. cerevisiae strains incorrectly identified may have been contaminants or the result of incorrect optimization conditions for the fermentation. Thus MALDITOF MS was shown to be an accurate identification tool, that may also be used to detect contaminants or incorrect environmental conditions which can result in substantial losses

Education and the gender wage gap in South Africa.

M. Com. University of KwaZulu-Natal, Durban 2015.A vast literature on the gender wage gap across different institutional structures and economies exists. Men typically earn more than women, with this gap being attributed to differences in productive characteristics, occupational choice and discrimination. However less research exists on how this gap differs by level of education. Using the National Income Dynamics Study (NIDS) Wave 1 2008, this study aims to analyse the prevailing gender wage gap by level of education in South Africa. Using quantile regression I estimate the size of the gender wage gap at different points of the wage distribution, by the worker’s level of education. Following the decomposition technique of Machado and Mata (2005) I then decompose the gender wage gap between men and women into different components. A key finding of this study is the presence of a glass ceiling for South Africa, which limits the ability of women’s wages at the top of the earnings distribution to rise to match the wages of men

Protein-carbohydrate interactions

Carbohydrates are ubiquitous in nature and have become the focus of much scientific investigation. The proteins which recognise carbohydrates have become widely used in the areas of cell and molecular biology. Protein - carbohydrate interactions have been probed by theoretical, structural and thermodynamic techniques. The lectins are a class of carbohydrate binding proteins which bind carbohydrates through non covalent interactions such as hydrogen bonds and van der Waals interactions. In addition to these interactions, other factors play an important role in determining affinity such as carbohydrate conformation, solvent reorganisation and changes in the protein binding site. The legume lectin concanavalin A specifically recognises mannose and glucose terminal residues. The thermodynamics of concanavalin A binding to carbohydrates has been well documented. Concanavalin A binds the core trimannoside and pentasaccharide of the biantennary glycan found on mammalian cell surfaces with a high affinity. This thesis describes the structural basis of carbohydrate binding by con A, through the interpretation of crystal structures of concanavalin A bound with α1-2 mannobiose, methyl α1-2 mannobioside, the core pentasaccharide of the biantennary glycan and fructose. The structural information obtained from these structures is related to thermodynamic information available and unravels the importance of the role played by carbohydrate conformation, solvent reorganisation and statistical population of ligand in determining affinity. This work helps to develop an understanding of the physical basis of carbohydrate recognition

Recyclage de déchets de production de composites thermoplastiques par moulage en compression

Cette étude traite d’une nouvelle méthode permettant le recyclage de composites thermoplastiques. Les matériaux concernés peuvent être des déchets de production de pièces primaires ou des pièces en fin de vie à recycler. Dans ce travail, des stratifiés bidirectionnels de verre/ polypropylène sont utilisés comme matériau de base. Le recyclage mécanique traditionnellement utilisé des étapes de déchiquetage qui engendrent des grains grossiers et est suivi par une étape de broyage permettant l’obtention d’un matériau plus fin qui est utilisé comme charge pour des composites injectés. Cependant, ces deux étapes ont pour conséquence de réduire les longueurs de fibres de façon conséquente et limite l’utilisation des composites recyclés. Ce travail propose donc d’étudier un concept différent qui consiste à ne pas utiliser de séquence de broyage mais de seulement garder une phase de découpe afin de limiter les défauts engendrés lors des étapes de déchiquetage et de broyage tout en gardant des longueurs de fibres les plus élevées pour maximiser le potentiel du matériau recyclé. Les grains de taille centimétrique obtenus sont alors directement réutilisés via le procédé de moulage par thermocompression. Cette étude montre que le module des pièces recyclées est très proche de celui des pièces initiales quasi isotropes pour des taux de fibres équivalents. Cependant, une baisse très significative des contraintes à rupture a été observée, et des pistes permettant de rehausser ces valeurs sont proposées

Production waste management of thermoplastic composites using compression moulding.

This study focuses on the mechanical recycling technique applied to fibre reinforced thermoplastics. The material studied are production scrap and off-cuts of bi-directional woven glass reinforced polypropylene pre-consolidated laminates. The traditional mechanical recycling technique involves a shredding step, giving coarse grains, followed by a grinding step, giving a finer material which is afterwards used as reinforcement in thermoplastic injection processes. However, from those two steps, degradation issues related to the reinforcement effective length limiting the reused material to low-end applications are encountered. The concept under study in this research work consists in by-passing the grinding step and to keep only a shredding or cutting step so as to limit the degradation of the initial material potential and keep a substantial reinforcement length. The obtained grains/aggregates are then directly reprocessed in bulk form by compression moulding. This preliminary study showed that the modulus of the recycled composite demonstrated values close to the equivalent quasi-isotropic continuous fibre laminate of the same composition

Valorisation matières de chutes de production de thermoplastiques par le procédé de thermo-compression

Cette étude traite d'une nouvelle méthode permettant le recyclage de composites thermoplastiques. Les matériaux concernés peuvent être des déchets de production de pièces primaires ou des pièces en fin de vie à recycler. Dans ce travail, des stratifiés bidirectionnels de verre/ polypropylène sont utilisés comme matériau de base. Le recyclage mécanique traditionnellement utilisé des étapes de déchiquetage qui engendrent des grains grossiers et est suivi par une étape de broyage permettant l'obtention d'un matériau plus fin qui est utilisé comme charge pour des composites injectés. Cependant, ces deux étapes ont pour conséquence de réduire les longueurs de fibres de façon conséquente et limite l'utilisation des composites recyclés. Ce travail propose donc d'étudier un concept différent qui consiste à ne pas utiliser de séquence de broyage mais de seulement garder une phase de découpe afin de limiter les défauts engendrés lors des étapes de déchiquetage et de broyage tout en gardant des longueurs de fibres les plus élevées pour maximiser le potentiel du matériau recyclé. Les grains de taille centimétrique obtenus sont alors directement réutilisés via le procédé de moulage par thermocompression. Cette étude montre que le module des pièces recyclées est très proche de celui des pièces initiales quasi isotropes pour des taux de fibres équivalents. Cependant, une baisse très significative des contraintes à rupture a été observée, et des pistes permettant de rehausser ces valeurs sont proposées

Complex shape forming of a flax woven fabric; analysis of the tow buckling and misalignment defect

With the view to minimise the impact on the environment and to produce structural parts with a goodproduction-rate/cost-ratio, the sheet forming of woven flax based fabric was investigated in this study. Aflax fibre plain-weave fabric has been used to form a complex tetrahedron shape. This shape is of partic-ular interest as it contains several geometric singularities required by many automotive parts such asdouble or triple curvature and low-curvature edges. Globally, the complex tetrahedron shape wasobtained, but tow buckling (out of plane bending of tows) was observed in specific zones of the shape.The main mechanism at the origin of this defect has been defined. A reduction of the tow buckle sizewas obtained by increasing the membrane tension. The influence of fabric architecture at the mesoscopicand macroscopic scales on the appearance of the tow buckles was demonstrated and discussed. Solutionsto prevent the appearance of this defect based on the design of the fabric architecture at the tow or fabricscales were successfully proposed. As a consequence, when sheet forming of complex shapes is consid-ered, specific fabric architectures should be chosen to prevent the appearance of the buckling defec

Non-Glycosidically Linked Pseudodisaccharides: Thioethers, Sulfoxides, Sulfones, Ethers, Selenoethers, and Their Binding to Lectins

Hydrolytically stable non-glycosidically linked tail-to-tail pseudodisaccharides are linked by a single bridging atom remote from the anomeric centre of the constituent monosaccharides. Some such pseudodisaccharides with sulfur or oxygen bridges were found to act as disaccharide mimetics in their binding to the Banana Lectin and to Concanavalin A. A versatile synthetic route to a small library of such compounds is described.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/69166/1/1951_ftp.pd